1. Field of the Invention
The present invention relates to an integrated twist grip shift for shifting gears of a bicycle transmission such as multistage hub transmissions or derailleurs.
2. Description of the Related Art
A twist grip shift for controlling a bicycle transmission is disclosed in European Patent EP 0700827 and includes a shift housing with a shift mechanism, a clamping device to be secured to a handlebar of the bicycle, a rotatable take-up reel coupled to a bearing tube for the elastic twist grip part, and a grip end part which is seated on the handlebar so that it is fixed with respect to rotation relative to the handlebar and is also elastic. The separate grip end part is as a rule an elastomer tube which is mounted on the handlebar in a frictionally locking manner and essentially transmits the manual supporting forces onto the handlebar and prevents unintentional shifting operations. A plastic intermediate ring may additionally be arranged between the rotatable twist grip part and the fixed elastomer tube to reduce the friction therebetween.
The twist grip part, the separate grip end part and the intermediate ring are individually fitted onto the handlebar and secured during the final mounting operation, with an appropriate degree of effort in terms of assembly and adjustment.
Since the separate grip end part is connected to the handlebar only by friction, there is a remote possibility that the hand together with the separate grip end part may slip off the handlebar during a critical situation.
The object of the present invention is to provide a twist grip shift with an integrated attachment of the grip end part such that the entire twist grip shift is supplied and mounted as a functional unit. The object is achieved by an integrated twist grip shift mountable on a handlebar tube of a bicycle for activating a bicycle transmission via a Bowden cable including a bearing tube, a twist grip part rotatably arranged on the bearing tube, a shift housing mountable on the handlebar tube and connected to the bearing tube via a releasable connection such that the shift housing is axially nondisplaceable and rotatably fixed relative to the shift housing. The twist grip shift further includes a clip arrangeable in a blocking position in the shift housing for securing the shift housing on the handlebar tube, the releasable connection being blocked by the clip when the clip is in the blocking position such that the releasable connection is releasable only when the clip is removed from the blocking position.
A further object of the present invention is to increase the protection of the twist grip shift during use by avoiding undesired displacement of the grip end part up with the possibility of slipping off the handlebar.
The present invention includes a bearing tube having elastic tongues. The elastic tongues have locking profiles at their respective ends which project in the radial direction to form a positively locking connection with a corresponding profile on a shift housing which protects against twisting and displacement. These elastic tongues allow the twist grip part, the take-up reel and the shift housing to be lined up with the shift mechanism and premounted as an assembly on the bearing tube. This assembly is protected against coming apart unintentionally by the connection between the bearing tube and shift housing. This appreciably reduces the number of twist grip components to be made available and to be mounted for final mounting on the handlebar. The entire twist grip shift is an integral unit which is ready for mounting. A clip is arranged in the internal diameter of the shift housing and may be tightened with an associated screw. Tightening the screw on the clip ensures a secure seat of the twist grip shift including the grip end part on the handlebar. The bearing tube and the twist grip part with the take-up reel are prevented from being dismounted again or disconnected from the shift housing until the clip is removed. To ensure a play-free seat on the handlebar, the internal diameter on the bearing tube and on the grip end part are given appropriately tight dimensions or tolerances. Selective deformation of the internal region may also be used to alleviate the tolerance sensitivity. For example, the inner face of the bearing tube may be of an oval or polygonal shape, instead of circular, to achieve a play-free seat during the adaptation to the round cross section. The oval or polygonal shape is preferably arranged in a region axially adjacent to the elastic tongues. The same effect may alternatively be achieved if the inner region of the bearing tube is equipped with narrow elevations which run essentially in the axial direction. The narrow elevations are deformed during mounting and then seated tightly to provide a play-free seat. Openings may be provided on the bearing tube in the region of the covering of the grip end part so that material projects into the internal diameter of the bearing tube when the grip end part is applied thereto. The material is then appropriately deformed and pressed on during the final mounting of the assembly on the handlebar.
The bearing tube is lengthened in the direction of the grip end part. The grip end part is secured on the bearing tube with a chemical overmolding connection. In contrast to the described prior art, the bearing tube of the present invention not fixed in terms of rotation to the elastic twist grip part and the take-up reel. Rather, the bearing tube of the present invention serves merely as a bearing for the take-up reel and forms, with a fixed intermediate ring, the necessary axial stop for the twist grip part which is fixedly connected in terms of rotation to the take-up reel.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.